1Preferred(3) User Contributed Perl Documentation Preferred(3)
2
6 Lingua::Preferred - Perl extension to choose a language
7
9 use Lingua::Preferred qw(which_lang acceptable_lang);
10 my @wanted = qw(en de fr it de_CH);
11 my @available = qw(fr it de);
12 my $which = which_lang(\@wanted, \@available);
14 print "language $which is the best of those available\n";
15 foreach (qw(en_US fr nl de_DE)) {
17 print "language $_ is acceptable\n"
18 if acceptable_lang(\@wanted, $_);
19 }
20
22 Often human-readable information is available in more than one
23 language. Which should you use? This module provides a way for the
24 user to specify possible languages in order of preference, and then to
25 pick the best language of those available. Different 'dialects' given
26 by the 'territory' part of the language specifier (such as en, en_GB,
27 and en_US) are also supported.
28 The routine "which_lang()" picks the best language from a list of
30 alternatives. The arguments are:
31 · a reference to a list of preferred languages (first is best).
33 Here, a language is a string like 'en' or 'fr_CA'. ('fr_*' can
34 also be given - see below.) 'C' (named for the Unix 'C' locale)
35 matches any language.
36 · a reference to non-empty list of available languages. Here, a
38 language can be like 'en', 'en_CA', or "undef" meaning 'unknown'.
39 The return code is which language to use. This will always be an
41 element of the available languages list.
42 The cleverness of this module (if you can call it that) comes from
44 inferring implicit language preferences based on the explicit list
45 passed in. For example, if you say that en is acceptable, then en_IE
46 and en_DK will presumably be acceptable too (but not as good as just
47 plain en). If you give your language as en_US, then en is almost as
48 good, with the other dialects of en following soon afterwards.
49 If there is a tie between two choices, as when two dialects of the same
51 language are available and neither is explicitly preferred, or when
52 none of the available languages appears in the user's list, then the
53 choice appearing earlier in the available list is preferred.
54 Sometimes, the automatic inferring of related dialects is not what you
56 want, because a language dialect may be very different to the 'main'
57 language, for example Swiss German or some forms of English. For this
58 case, the special form 'XX_*' is available. If you dislike Mexican
59 Spanish (as a completely arbitrary example), then "[ 'es', 'es_*',
60 'es_MX' ]" would rank this dialect below any other dialect of es (but
61 still acceptable). You don't have to explicitly list every other
62 dialect of Spanish before es_MX.
63 So for example, supposing @avail contains the languages available:
65 · You know English and prefer US English:
67 $which = which_lang([ 'en_US' ], \@avail);
69 · You know English and German, German/Germany is preferred:
71 $which = which_lang([ 'en', 'de_DE' ], \@avail);
73 · You know English and German, but preferably not Swiss German:
75 $which = which_lang([ 'en', 'de', 'de_*', 'de_CH' ], \@avail);
77 Here any dialect of German (eg de_DE, de_AT) is preferable to
79 de_CH.
80 Whereas "which_lang()" picks the best language from a list of
82 alternatives, "acceptable_lang()" answers whether a single language
83 is included (explicitly or implicitly) in the list of wanted
84 languages. It adds the implicit dialects in the same way.
85
87 Ed Avis, ed@membled.com
88
90 perl(1).
91
93 Hey! The above document had some coding errors, which are explained
94 below:
95 Around line 258:
97 You forgot a '=back' before '=head1'
98perl v5.12.0 2003-12-14 Preferred(3)